1. Field of the Invention
The present invention relates to a jig for attachment and detachment of an electronic component such as an MCM (multi-chip module) to and from a connector such as a so-called ZIF (zero insertion force) connector mounted on a printed circuit board.
2. Description of the Prior Art
When an electronic component such as an MCM is mounted on a printed circuit board, electric connection is established between a plurality of input/output pins protruding from the rear surface of the MCM and a plurality of corresponding input/output pads arranged on the upper surface of the printed circuit board. Such electric connection can be achieved by a ZIF connector mounted on the printed circuit board. The ZIF connector is supposed to allow attachment and detachment of the MCM to and from the printed circuit board without applying a damaging stress to the input/output pins of the MCM.
A ZIF connector usually comprises a pair of upper and lower substrates sequentially superposed on the surface of the printed circuit board. A plurality of sockets are formed in the ZIF connector so as to receive the input/output pin of the MCM. The respective sockets comprise an upper through hole penetrating through the upper substrate and a lower through hole penetrating through the lower substrate. When the upper substrate is slid relative to the lower substrate, the upper through holes are shifted to a position off the corresponding lower through holes. Such sliding movement of the upper substrate allows the input/output pins to be held between the inner surfaces of the upper and lower through holes. Since a larger contact friction can be maintained between the upper and lower substrates, the input/output pins can reliably be held between the inner surfaces of the upper and lower through holes.
When an MCM is to be coupled with a ZIF connector, the MCM must be properly positioned relative to the ZIF connector, so that the respective input/output pins of the MCM are aligned with the corresponding sockets of the ZIF connector. Such alignment allows the sockets to receive the corresponding input/output pins. If an operator is forced to manually mount the MCM on the ZIF connector, the operator must carefully observe the position of the MCM with his own eyes. It is impossible to completely avoid collision of the input/output pins against the entrances of the sockets at their tip ends. The input/output pins suffer from damages such as deformation.
In particular, maintenance of computer systems often requires attachment and detachment of an electronic component such as an MCM to and from a printed circuit board without disassembling the printed circuit board from the computer system. Without disassembly of the printed circuit board, it is possible to avoid a troublesome operation of disconnecting and connecting a large number of wires and cables from and to the printed circuit board. The maintenance can be simplified. However, it is more difficult to an operator to align the input/output pins of the MCM with the corresponding sockets of the ZIF connector during the maintenance, since the ZIF connector is surrounded by other printed circuit boards and electronic components, which tend to block the operator""s field of view.
It is accordingly an object of the present invention to provide a jig for attachment and detachment of an electronic component, useful to simply and efficiently allow input/output pins of the electronic component to enter corresponding sockets or holes of a connector, thereby improving the operability.
According to the present invention, there is provided a jig for attachment and detachment of an electronic component, comprising: a frame; a connector receptacle opening defined in the frame so as to have dimensions enough to surround a connector mounted on a printed circuit board; an insertion opening defined in the frame so as to have dimensions enough to surround an electronic component with an input/output pin received in the connector; and a guide passage defined in the frame so as to extend from the insertion opening to the connector receptacle opening.
When an electronic component is to be set on a connector mounted on a printed circuit board, for example, the frame is set on the surface of the printed circuit board so as to surround the connector. The connector is received in the connector receptacle opening of the frame. The frame is designed to stand on the surface of the printed circuit board surrounding the connector. The electronic component is thereafter inserted into the insertion opening. The electronic component is then allowed to move along the guide passage toward the connector receptacle opening. The guide passage serves to allow the input/output pin of the electronic component to reliably enter the socket of the connector without any interference. An operator is released from careful observation for alignment of the electronic component with the connector with his own eyes.
Such a jig may be employed to attach an electronic component such as an MCM (multi-chip module) to a so-called ZIF (zero insertion force) connector. In this case, the jig may comprise a swinging lever supported on the frame so as to engage with a rotative cam for opening and closing a socket of the connector. In general, the upper substrate is driven to slide on the lower substrate electrically connected by soldering to the printed circuit board in a ZIF connector. Such sliding movement allows the socket to fully open. A rotative cam is usually employed to establish the driving force applied to the upper substrate. The rotative cam is designed to generate the driving force with a cam surface offset to the rotation axis of the rotative cam when the rotative cam is driven for rotation. The rotative cam should receive a torque enough to overcome the contact friction induced between the upper and lower substrates. Employment of the swinging lever serves to amplify a small torque, applied to the free end of the swinging lever, to a larger torque received by the rotative cam. The swinging lever is preferably kept in an attitude perpendicular to the rotation axis of the rotative cam.
When the swinging lever is employed in the above-described manner, the jig may further comprise: an operating lever supported on the frame for swinging movement around a support axis; and a link member connected to the operating lever at a first connecting axis for swinging movement and to the swinging lever at a second connecting axis for swinging movement. The operating lever and the line member are designed in combination to establish a link mechanism.
If the distance between the support axis and the first connecting axis is set larger than the distance between a center of swinging movement of the swinging lever and the second connecting axis in the link mechanism, the swinging movement of the operating lever can be amplified and transformed to the swinging movement of the swinging lever. A less extent of the swinging movement is only required for the operating lever so as to induce rotation of the rotative cam required to achieve opening and closing operation of the socket. Such an extent of the swinging movement serves to prevent the tip end of the operating lever from projecting outward of the frame. Even when other printed circuit board and/or electronic components are disposed to closely surround the connector, attachment and detachment of the electronic component can reliably be achieved without any interference in such a crowded circumstance.
The jig may further comprise a first restriction member located on the frame at a position to collide with the operating lever when the socket of the connector is closed, in addition to a second restriction member located on the frame at a position to collide with the operating lever when the socket of the connector is opened. The first and second restriction members are adapted to reliably restrict the extent of the movement of the operating lever. Accordingly, the rotative cam of the connector can be prevented from an excessive rotation beyond the extent required to fully open and close the socket of the connector. The connector can be prevented from damages due to any excessive rotation of the rotative cam.
The jig may further comprise a grip attached to the free or tip end of the operating lever. The grip is preferably designed to extend across the insertion opening when the socket is closed. Such a grip serves to avoid an erroneous insertion of an electronic component into the guide passage when the socket is closed. The electronic component can reliably be prevented from colliding against the closed socket. The input/output pin of the electronic component can thus be prevented from damaging.
Furthermore, the jig may further comprise a fixation mechanism adapted to fix the frame to the printed circuit board. Such a fixation mechanism may serve to release an operator from troublesome operation to keep urging the jig against the printed circuit board during an overall period of maintenance. The operation of maintenance can be simplified. In particular, such a fixation mechanism is most useful when the printed circuit board is kept upright in a vertical direction.
The fixation mechanism may comprise: a leaf spring attached to the frame so as to keep a free end thereof apart from the frame; a hook formed at the free end of the leaf spring so as to keep retracted out of the connector receptacle opening when no load is applied to the leaf spring; and a slider member guided along an outer periphery of the frame so as to apply an urging force to the leaf spring for bringing the hook into engagement with the connector in response to deformation of the leaf spring. Such a fixation mechanism is designed to allow the hook at the free end of the leaf spring to be released from engagement with the connector when no load is applied to the leaf spring, so that the jig can be removed from the connector or the printed circuit board. On the other hand, when the slider member moves to apply the urging force to the leaf spring, the leaf spring is deformed to establish engagement of the hook with the rear of the connector. The jig can be fixed to the connector in this way. Specifically, only a simple movement of the slider member along the outer periphery of the frame is required to establish and release engagement or fixation of the jig to the printed circuit board.
When the hook is released from engagement with the connector, it is preferable to terminate the operation of attachment or detachment of an electronic component. If such operation is maintained with the jig detached from the printed circuit board, the jig may be shifted or slid during the operation of attachment or detachment. The connector and/or the input/output pin of the electronic component are possibly damaged. According to the present invention, a stopper may be employed to prevent such incorrect operation. The stopper may be adapted to extend across a path of movement of the operating lever when the fixation mechanism fails to fix the frame to the printed circuit board or when the slider member fails to establish the urging force to the leaf spring.
In addition, when the socket is opened in the connector, it is preferable to avoid removal of the jig, since such removal causes the connector to suffer from damages and/or trouble in subsequent attachment of an electronic component. According to the present invention, a drop prevention member may be employed to prevent such undesirable removal. The drop prevention member may be located right on a path of movement of the slider member when the socket is opened.
Otherwise, the jig may further comprise a restriction member protruding into the guide passage, for example. Such restriction member may serve to always mount an electronic component of a proper attitude or aspect on the connector. The input/output pin can further reliably be prevented from damaging.
Furthermore, the jig may further comprise an observation window defined by an edge aligned with an upper edge of the electronic component when the electronic component has been completely set on the connector. Such an observation window may serve to prevent the socket to be opened and closed before the electronic component is completely mounted on the connector.